نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشجوی سابق دکترای تکنولوژی مواد غذایی دانشکده کشاورزی دانشگاه تبریز، استادیار مرکز تحقیقات کشاورزی و منابع طبیعی آذربایجان غربی
2 دانشکده کشاورزی، دانشگاه تبریز
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
Background and objectives: In spite of high advantages of UF-Feta cheeses, especially their high yield, ripening and aroma and flavor development in theses cheeses occurs more slowly than traditional cheeses. Cheese ripening is a complex and inevitable process to obtain a product with unique organoleptic and textural characteristics. During the ripening, the cheese is subjected to changes, including glycolysis, lipolysis and proteolysis. Proteolysis is the most important and complex event that occurs in a great number of cheese varieties during ripening and strongly affects the sensory properties of the cheese.Therefore, in this study the effect of cas-amino acids addition on acceleration of proteolysis and flavor and aroma development in these cheeses during 60 days ripening period was investigated.
Materials and methods: Cheese samples were made in 3 trials on 3 consecutive days. Control treatment was produced according to the plant conventional method. In experimental treatment, cas-amino acids, were added into retentate in addition to starter and rennet. Chemical composition, pH 4.6-soluble nitrogen, urea-PAGE, peptide profiles, total and individual amino acids and sensory properties of cheese samples during 60 days ripening period were evaluated.
Results: Results showed that there are no significant differences in terms of chemical composition and pH between one-day-old experimental and control cheeses. Soluble nitrogen in pH=4.6 was significantly (P< 0.05) higher during whole ripening period except first day in treatment contained free amino acids. Polyacrylamide gel electrophoresis of the pH 4.6-insoluble fraction showed no significant difference in terms of the hydrolysis rate of αs1-casein between control and experimental treatments during ripening. Rate of β-casein hydrolysis was more slowly in both treatments during ripening. In RP-HPLC chromatograms of the pH 4.6-soluble fractions of 60-day-old samples, the ratio of hydrophilic to hydrophobic peptides was higher in experimental cheese than that of control cheese. In experimental treatment, the concentrations of total free amino acids were significantly (P< 0.05) higher in whole ripening period. Levels of index individual free amino acids also were considerably higher in experimental cheese at 60 day. In terms of sensory characteristics, free cas-amino acids containing treatment, had a significant difference (P< 0.05) with the control sample, and obtained more scores for flavor, aroma and overall acceptability.
Conclusion: Generally, the addition of free cas-amino acids into retentate had positive effect on the proteolysis acceleration and as a result, ripening and flavor and aroma improvement as well as overall acceptability of UF-Feta cheese.
Key words: Free Cas-amino acids, Proteolysis, UF-Feta cheese
کلیدواژهها [English]